In his Freakonomics blog on the New York Times, economist Steven D. Levitt issues a stirring defense of freedom of speech and scientific inquiry. Well, no, actually, Levitt sidesteps that whole tarpit and instead complains that he, Levitt, should have gotten more publicity.

Nobel Laureate James Watson got into trouble recently for expressing the opinion that blacks are less intelligent than whites.

If you look at almost all existing data from standardized tests in the United States, there is indeed a sizable black-white test score gap. Whether the gap is due to genetic differences is a hotly debated academic question.

Roland Fryer and I have done some research on this topic which we think is potentially quite interesting and important although we seem to be the only ones with this opinion at present. (The paper was rejected yesterday by the American Economic Review on the second round of review, and a search of Google Scholar reveals only two citations to the working paper version released in early 2006.)

In my work with Fryer, we analyzed a newly available nationally representative survey of children ages two and under, done by the Department of Education. Included in this study are tests of mental ability around a childs first birthday. While you might think it would be impossible to capture anything meaningful at such a young age, it turns out that these measures of one-year-olds intelligence are somewhat highly correlated with IQ scores at later ages, as well as with parental IQ scores.

The striking result we find is that there are no racial differences in mental functioning at age one, although a racial gap begins to emerge over the next few years of life.

So what does this mean for the genetics vs. environment debate? Quoting from our abstract, the observed patterns are broadly consistent with large racial differences in environmental factors that grow in importance as children age. Our findings are not consistent with the simplest models of large genetic differences across races in intelligence, although we cannot rule out the possibility that intelligence has multiple dimensions and racial differences are present only in those dimensions that emerge later in life.

Like all research, our study has its flaws and limitations. I have to say, however, that I imagined a lot of reactions to this paper, none of which were utter indifference on the part of academics and the popular press. But that was the reaction we got.

I just did a study of lactose tolerance among one-year-olds, and guess what? I didn't find any racial differences! They were all lactose tolerant. So all those stories you hear about how East Asians don't have a gene for lactose tolerance are just racist myths! I proved it with science!

I also did a study of one-year-olds' ability to slam dunk on a ten foot basket. Once again, there were no racial differences. None of them could dunk. I even lowered the basket to six feet and still there were no racial differences in dunking. So, when you watch the NBA and there are all these blacks guys slam dunking, that's just racism. Who are you gonna believe, science or your lying eyes?

Then, I got a bunch of Kenyan and Ethiopian highlander one-year-old babies together with some other babies and timed them in the marathon. As always, there were no racial differences. Not a single baby of any origin finished the 26.2 mile run. So, the next time the top ten finishers at a big marathon are eight Kenyans and two Ethiopians, don't believe it!

Seriously, I always love how the New York Times is oh-so-skeptical about IQ testing in general, except when it supports something they like, and then credulity is the order of the day. Look, there is no IQ test for 1-year-olds. What Levitt did in this paper is show that a test of infant liveliness (e.g., how often the infant babbles) that has a fairly low but positive correlation with childhood IQ [which, by the way, is quite common — it's harder to find something that is not at all correlated with IQ — drumming ability is the most famous example of something with no IQ correlation].

So, this test of liveliness of 8 to 12 month olds doesn't show the IQ differences seen among older children. Indeed, the highest IQ children (Northeast Asians) do the worst on this test of infant vivacity. With a typical Freakonomic leap of faith, Levitt and Fryer suggested that this shows that IQ differences aren't genetic but are caused by environmental differences, presumably between age 1 and the earliest ages at which IQ tests are semi-reliable.

Of course, all Levitt actually did was show that this test of infant liveliness is a racially biased predictor of IQ. Why is it racially biased? Well, there are lots more ways for something to go wrong than to go right, but one obvious possibility is that the test of infant alertness might measure traits that differ on average between the races, but aren't related to IQ differences between the races. For example, within a race, babies that babble more turn out to be a little bit smarter on average than more taciturn babies. Yet, Asian infants don't babble as much on average as other babies, but that doesn't mean they'll turn out to have lower IQs on average than babies from races that babble more. But pointing out that this test of babies is racially biased is not as sexy a story as claiming it shows Nurture Triumphs Over Nature.